KR100707595B1 - Method for forming isolation layer of semiconductor device - Google Patents

Abstract

In the method of forming an isolation layer of a semiconductor device according to the present invention, a nitride film is formed on a silicon substrate, and a photoresist pattern is formed on the nitride film by using a photo process. Thereafter, the nitride film is selectively etched using the photoresist pattern as a mask to form a nitride film pattern having an opening for exposing the substrate to a predetermined width. Next, an element isolation film is formed in the opening between the nitride film patterns. Thereafter, the nitride film pattern is removed, and a polysilicon layer is formed on the substrate on which the device isolation film is formed. Herein, it is preferable to form the device isolation film using an RTP process. In addition, the polysilicon layer is preferably formed lower than the thickness of the device isolation film. According to the present invention, the device isolation film is formed by a thin film manufacturing process, so that the device isolation film can be formed more easily than the trench type device isolation film, and the degree of integration of the device can be improved.

Shallow Trench Isolation (STI), Device Isolation Layer, Rapid Thermal Process (RTP)

Description

Method for Forming Isolation Layer of Semiconductor Device {Method for Forming Isolation Layer of Semiconductor Device}

1 is a cross-sectional view illustrating a trench device isolation layer formed by a conventional method.

2 to 7 are cross-sectional views sequentially illustrating a method of forming a device isolation layer of a semiconductor device according to the present invention.

<Description of Major Symbols in Drawing>

10: silicon substrate 20: trench

20a: trench inlet 22: pad oxide film

24: pad nitride film 30: trench oxide film

40: nitride film 40a: photosensitive film pattern

42: nitride film pattern 50: device isolation film

60: polysilicon layer 70: gate oxide film

80: gate

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology for manufacturing a semiconductor device, and more particularly, to a device isolation film forming method of a semiconductor device capable of improving the degree of integration of a semiconductor device by forming a device isolation film in a thin film manufacturing process.

In order to realize high integration of the semiconductor device, it is necessary to form various semiconductor elements constituting the semiconductor device, for example, transistors, capacitors, and various wirings in a very narrow area. Therefore, since the distance between each component which comprises a semiconductor device is narrow, it is necessary to further strengthen the insulation between each component. Conventionally, a LOCOS field oxide film, which is formed by locally oxidizing a silicon substrate, has been widely used as a means for electrically separating semiconductor elements constituting a semiconductor device.

However, the locos type field oxide film interferes with high integration of the semiconductor device because the locus-type field oxide film partially invades the active region where the semiconductor devices are formed due to a bird's beak generated in the formation process. Therefore, a field oxide film having a small area and excellent insulation is required. A representative example is a trench field oxide film, and a shallow trench isolation (STI) is particularly widely used.

A method of forming a conventional STI will now be described with reference to FIG. 1. The pad oxide film 22 and the pad nitride film 24 are sequentially formed on the silicon substrate 10.

Then, a photoresist is applied onto the pad nitride film 24, and then a photoresist pattern (not shown) is formed to separate the active and field regions of the substrate through a photolithography process.

Next, the pad nitride film 24 and the pad oxide film 22 are sequentially etched using the photoresist pattern as the etch stop film. At the same time or in a separate process, the inside of the substrate 10 is etched to a predetermined depth to form a trench 20. After the trench 20 is formed in this manner, the photoresist pattern is removed through a cleaning process.

Next, the silicon surface is modified by forming a thin STI lining oxide inside the trench 20 through a thermal oxidation process. Then, a trench oxide 30 such as a chemical vapor deposition (CVD) oxide or a high density plasma CVD oxide using a tetraethly orthosilicate (TEOS) oxide film is embedded in the trench 20.

Next, the trench oxide 30 is deposited on the entire surface of the pad nitride layer 24. Immediately after filling the trench 20, the surface thereof becomes uneven due to the lower bend, so that the trench oxide 30 is used for the subsequent process. The front side of the is planarized using a chemical mechanical polishing (CMP) process.

Next, the pad oxide film 22 and the pad nitride film 24 on the substrate 10 are wet-etched and removed to complete the STI used as the device isolation film.

The STI formed as described above is compact in accordance with the high integration of semiconductor devices. In the case of the STI having a CD (Critical Dimension) of 0.25 μm or less, it is not easy to embed the STI oxide 30 inside the trench 20. . That is, since the width of the trench 20 is formed too small, the inlet 20a is narrow and cannot be faithfully embedded in the trench 20. If the inlet 20a of the trench 20 is too narrow, CVD oxide is mainly deposited near the upper edge of the trench 20, increasing the risk of voids being formed inside the trench.

In addition, the oxide used in the device isolation layer uses a TEOS oxide film. The TEOS oxide film is weak in hardness and is reduced during a subsequent thermal process, and thus has a disadvantage of easily causing defects at the interface.

The present invention provides a method of forming a device isolation film of a semiconductor device capable of improving the degree of integration of the semiconductor device by forming a device isolation film in a thin film manufacturing process.

A method of forming a device isolation film of a semiconductor device according to the present invention includes forming a nitride film on a silicon substrate, forming a photosensitive film pattern on the nitride film using a photo process, and selectively etching the nitride film using the photosensitive film pattern as a mask. Forming a nitride film pattern so as to form an opening that exposes a predetermined width, forming a device isolation film in the opening between the nitride film pattern, removing the nitride film pattern, and forming a polysilicon layer on the substrate on which the device isolation film is formed. Forming a step.

Herein, it is preferable to form the device isolation film using an RTP process. In addition, the polysilicon layer is preferably formed lower than the thickness of the device isolation film.

Example

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

In the following description, descriptions of technical contents which are well known in the technical field to which the present invention belongs and are not directly related to the present invention will be omitted. This is to more clearly communicate without obscure the subject matter of the present invention by omitting unnecessary description. For the same reason, some components in the accompanying drawings are somewhat exaggerated, omitted, or schematically illustrated, and the size of each component does not necessarily reflect the actual size.

2 to 6 are cross-sectional views illustrating a method of forming an isolation layer of a semiconductor device in accordance with an embodiment of the present invention.

Referring to FIG. 2, the nitride film 40 is formed on the silicon substrate 10. Here, the nitride film 40 forms a nitride film made of SiN using, for example, a Plasma Enhanced Chemical Vapor Deposition (PECVD) method.

Next, as shown in FIG. 3, the photoresist pattern 40a is formed on the nitride film 40 using a photolithography process. Thereafter, the nitride film pattern 42 is formed by selectively etching the nitride film 40 using the photoresist pattern 40a as a mask to form an opening 41 that exposes the substrate 10 to a predetermined width.

Next, as shown in FIG. 4, the isolation layer 50 is formed on the substrate 10 on which the nitride film pattern 42 is formed. Here, the device isolation layer 50 is formed using a rapid thermal process (RTP) process, which is a thin film manufacturing process.

In this case, since the device isolation layer 50 is formed of RTP, the oxide film does not grow in the region where the nitride film pattern 42 is present, and thus the device isolation film 50 is not formed on the nitride film pattern 42. It is formed only in the opening 41 which exposes the substrate 10 between 42 to a predetermined width.

In this case, the device isolation film 50 may be formed using RTP instead of being formed in a furnace equipment that is processed in a batch type, thereby increasing the process speed. Thereafter, as shown in FIG. 5, the nitride layer pattern 42 is removed to leave only the device isolation layer 50 on the substrate 10.

Next, as shown in FIG. 6, the polysilicon layer 60 is formed on the substrate 10 on which the device isolation layer 50 is formed. The polysilicon layer 60 is formed lower than the thickness of the device isolation layer 50. Here, the polysilicon layer 60 formed on the device isolation layer 50 is a part where the device is to be formed.

Next, as shown in FIG. 7, the gate oxide layer 70 and the gate 80 are formed in the polysilicon layer 60 on the device isolation layer 50. Thereafter, a general logic process is performed to form a device.

If the device isolation layer is formed in this manner, the degree of integration of the semiconductor device may be improved. In addition, the device isolation layer formed by the thin film manufacturing process may be easier than the trench type device isolation layer (STI).

In the method of forming a device isolation layer of a semiconductor device according to the present invention, the device isolation layer may be formed by a thin film manufacturing process, so that the device isolation layer may be formed more easily than the trench type device isolation layer, and the degree of integration of the device may be improved.

In addition, the method of forming a device isolation layer of the semiconductor device according to the present invention may increase the process speed since the device isolation layer is formed by using RTP instead of the furnace equipment that proceeds in a batch form.

Although preferred embodiments of the invention have been disclosed, although specific terms have been used, these are merely used in a general sense to easily explain the technical content of the present invention and to help understand the present invention, and are not intended to limit the scope of the present invention. . It will be apparent to those skilled in the art that other modifications based on the technical idea of the present invention can be carried out in addition to the embodiments disclosed herein.

Claims (3)

Forming a nitride film on the silicon substrate, Forming a photoresist pattern on the nitride film by using a photo process; Selectively etching the nitride film using the photoresist pattern as a mask to form a nitride film pattern having an opening for exposing the substrate to a predetermined width; Forming an isolation layer in the opening between the nitride film patterns; Removing the nitride film pattern; And forming a polysilicon layer on the substrate on which the device isolation layer is formed. In claim 1, The device isolation film forming method of the semiconductor device, characterized in that formed using a rapid thermal process (RTP) process. In claim 1, Wherein the polysilicon layer is formed to be lower than the thickness of the device isolation film.

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